Four college students and their professor are traveling by bus when a forced detour and a sudden crash strand them on the outskirts of Little Hope, an abandoned town in Massachusetts smothered in thick fog. With their driver missing and no way to call for help, the group ventures into the deserted streets, where they meet a wary local who warns them the place has long been empty. As they search for a way out, the fog repeatedly pulls them into visions of the town's 17th century past, where a manipulative reverend and a frightened young girl set the Andover and Salem witch trials in motion. The travelers come to realize that the accused townsfolk are eerie doppelgangers of themselves, and that demonic figures born of those historic executions are now stalking them through the present.